Growth Of Fruiting Bodies Research Articles

큰느타리버섯 신품종 '새곤지' 육성 및 특성

큰느타리버섯의 품종다양화와 보급확대를 목적으로 발생개체수가 적고 생력재배에 적합한 "새곤지"의 특성을 조사한 결과는 다음과 같다. 균사생장을 위한 적정온도범위는 <TEX>$23{\sim}26^{\circ}C$</TEX>로 대조품종 <TEX>$26{\sim}29^{\circ}C$</TEX>보다 낮았다. 자실체 발생 및 생육적온은 <TEX>$15{\pm}1^{\circ}C$</TEX>였으며, 재배기간은 51일로 대조품종과 동일하였다. 갓형태는 생육초기 반반구형에서 생육후기까지 평반구형의 갓형태를 유지하였다. 병당 발생개체수는 3.5개로, 대조품종 12.8개 대비 9.3개 적었다. 대길이는 135.8 mm로 대조품종 124.6 mm보다 길었고, 갓표면의 색도(Lightness)는 60.4로 대조품종 57.6보다 높아 연회색을 나타내었다. 탄력성과 응집성은 대등하였고, 깨짐성, 경도값은 각각 71,068 g, <TEX>$5,662g/cm^2$</TEX>으로 대조품종보다 낮았다. 병당수량은 900 cc/<TEX>$65{\Phi}$</TEX> 병에서 106.4 g, 1100 cc/<TEX>$75{\Phi}$</TEX> 병에서159 g으로 대조품종 과 대등하였다. We bred a new strain of Pleurotus eryngii having few number of fruit body per bottle. It's name is 'Saegonji' and it was bred by mating monokaryotic strain isolated from E12-176 and monokaryotic strain 'aerini No.3' in Mushroom Research Institute, Gyonggi province A.R.E.S. The characteristics of a new strain 'Saegonji' are as follows. The optimum temperature for mycelium growth was from 23 to <TEX>$26^{\circ}C$</TEX> on PDA medium and those for the primodium formation and the growth of fruit body were about <TEX>$15^{\circ}C$</TEX>. The period from spawn innoculation to harvesting required around 51 days at <TEX>$20^{\circ}C$</TEX>. The number of fruit body per bottle was 12.8 and it was 9.3 less than 'Keunneutari No.2'. The length was 135.8 mm. It was longer than 'Keunneutari No.2', The color of cap was white grey, while that of 'Keunneutari No.2' was grey. The yield was about 159 g per bottle(1100cc) and it was same as Keunneutari No.2.

LED lights increase bioactive substances at low energy costs in culturing fruiting bodies of Cordyceps militaris

Cordyceps militaris is widely cultured to produce fruiting bodies for medicinal and health food use. Illumination is an important factor for the growth, quality and production costs. The effects of different light-emitting diode (LED) light combinations on primordia induction, the growth and bioactive substances of fruiting bodies were investigated. The results showed that the monochromatic red or far-red LED failed to induce primordia. Blue light was a must for primordia induction and a red:blue 2:1 with 10% far-red induced the greatest frequency of primordia. Dry weights of fruiting bodies were lower under red and far-red LED treatments. Cordycepin contents in fruiting bodies were significantly higher in red and white (red:blue:far-red 6:3:1) LED treatments, with the increases up to 62% over the fluorescent control. Carotenoids content was significant lower in the red or far-red LED treatment than in other treatments. The results demonstrated the functions of different wavelength lights on the growth and biosynthesis of bioactive substances and that using the low heat release and energy consumption LED lights to replace the traditional fluorescent lights can improve the product quality and increase the contents of bioactive substances. A red to blue ratio of 2:1 with 10% far-red is the optimal light quality for culturing fruiting bodies of C. militaris.

푸른곰팡이 대치배양에 의한 꽃송이버섯 균사 생장 특성 및 계통간 교잡균주의 rDNA 분석

Cauliflower mushroom widely known high concent of β-glucan for farm cultivation invigoration verified characteristics of mycelia growth, genetic diversity, resistance to Trichoderma by replacement culture with Trichoderma and growth characteristics of new variety crossbleeding strain. The result of replacement culture with Trichoderma for verification resistance about Trichoderma, 6951 (T. viride) strain did not show special change after formation of confrontation line and 6952 (T. spp.) strain was showed more formation of spore after formation of confrontation line. But 6426 (T. harzianum) strain found to encroach part of growth area of cauliflower mushroom mycelia. Among 10 kinds cauliflower mushroom strain, JF02-06 strain collected by Gurye, found did not spore of Trichoderma and thought to be resistant to Trichoderma. The result of crossbleeding after selected that mother strain good growth and formation of fruit body, verified good mycelia growth at JF02-47, 49 and 50 strain in Korean pine of wood- chip media. The result of gene sequence about ITS1, 5.8S and ITS4 for analysis of genetic diversity at crossbleeding strain, found high significance to other cauliflower mushroom in registered Genebank. The result of growth characteristic of spore and mycelia of cauliflower mushroom by observation microscope, size of spore showed water drop shape to major axis 6 μm and minor axis 5 μm and clamp showed 3 types in mycelia. The wide of mycelia was 3 μm. The characteristic of mycelia of cauliflower mushroom found to grow mycelia in clamp at approximately 50%. The growth speed of mycelia was 0.507 μm/min and 2nd mycelia grown similar speed to mother mycelia at parallel with mother mycelia after growth speed at 0.082 μm/min. The formation of clamp made small clamp for 5 hours after shown transfer of electrolyte in mycelia inside. The septum formation started after 3 hours and then finally completed after 2 hours. In this study, strain of cauliflower mushroom verified resistance of Trichoderma, genetic diversity and characteristic of mycelia growth. Therefore, basic knowledge of cauliflower mushroom will improve and further contribute to development of mushroom industry.

Enhancement of β-Glucan Content in the Cultivation of Cauliflower Mushroom (Sparassis latifolia) by Elicitation

The effectiveness of three kinds of enzymes (chitinase, β-glucuronidase, and lysing enzyme complex), employed as elicitors to enhance the β-glucan content in the sawdust-based cultivation of cauliflower mushroom (Sparassis latifolia), was examined. The elicitors were applied to the cauliflower mushroom after primordium formation, by spraying the enzyme solutions at three different levels on the sawdust-based medium. Mycelial growth was fully accomplished by the treatments, but the metabolic process during the growth of fruiting bodies was affected. The application of a lysing enzyme resulted in an increase in the β-glucan concentration by up to 31% compared to that of the control. However, the treatment resulted in a decrease in mushroom yield, which necessitated the need to evaluate its economic efficiency. Although we still need to develop a more efficient way for using elicitors to enhance functional metabolites in mushroom cultivation, the results indicate that the elicitation technique can be applied in the cultivation of medicinal/edible mushrooms.

Purification and characterization of intracellular serine protease produced in mycelia during fruit-body growth stage of Hypsizygus marmoreus

Purification and characterization of intracellular serine protease produced in mycelia during fruit-body growth stage of Hypsizygus marmoreus

장기저장성 신품종 느타리버섯 『곤지7호』 육성 및 특성

병재배용 고품질 장기저장성 느타리 품종인 '곤지7호'의 주요특성을 요약하면 다음과 같다. 균사생장적온은 <TEX>$26{\sim}29^{\circ}C$</TEX>이고 버섯발생 및 생육온도는 <TEX>$16{\sim}18^{\circ}C$</TEX>로 중온성을 나타내었다. 병재배시 배양기간은 30일, 초발이 소요일수는 4일, 생육일수는 4일로 총재배기간은 38일이 소요되었다. 갓크기는 46.6 mm이며, 갓색은 진회색을 나타냈다. 대직경 12.4 mm, 대길이 84.8 mm로 굵고 긴형태이며, 대색은 백색을 나타내었다. 수량은 생산력검정시 900 ml병에서 166 g을 나타내었으며, 농가실증재배시 농가1에서는 187 g/ 1100 ml, 농가2에서는 197 g/1100 ml으로 대조품종과 대등하였다. 대의 물리성에서 있어, 탄력성 83%, 응집성 71%, 씹읍성 352 g, 깨집성 29 kg으로 '춘추2호'와 '수한1호'의 중간특성을 나타내었다. Minamide법에 준한 저장성은 35일까지 신선도 등급 6 (판매가능 등급) 으로 대조품종에 비하여 7일정도 저장기간이 연장되었다. DNA다형성을 비교 분석한 결과, UFPF3, UFPF5, UFPF7등의 primer에서 교배모본인 '농민59호'와 'MT07156'의 DNA의 밴드가 혼합되어 있었으며 품종간, 균주간의 밴드 차이가 있었다. The oyster mushroom is a wide cultivar among cultivated edible mushrooms in Korea. But, due to the excess of domestic production, the price has been falling. This study has been conducted to develope new variety oyster mushroom(Pleurotus ostreatus) which have a long term storage to export in foreign market as well as domestic. 'Gonji-7ho', a new variety of oyster mushroom, for the bottle culture, was bred by mating with monokaryons isolated from 'Nongmin-59ho' and 'MT07156'. In the characteristics of fruit body, pilei were round type and gray and stipes were white color and soft. The fruit body growth was vital and uniform. When fruit-body was stored at 4 degrees after packing with plastic vinyl, storage period was extended 7 days longer than 28 day of chunchu-2ho. The yield was 166 g per a bottle(￠65, 900 ml).

Extraction, preliminary characterization and antioxidant activity of Se-enriched Maitake polysaccharide

A Se-enriched Grifola frondosa polysaccharide (Se-GP) was obtained from G. frondosa enriched with Se by spraying an Na2SeO3 solution during fruit body growth using a Box–Behnken design and compared to G. frondosa polysaccharide (GP) for preliminary characterization and determination of the antioxidant activity. Under optimal conditions, polysaccharide yields and both the Se-GP and GP contents do not differ; however, the Se content of Se-GP (17.52μg/g) was 48.7 times that of GP. Three homogenous Se-GPs (Se-GP11, Se-GP22 and Se-GP33) or GPs (GP11, GP22 and GP33) were obtained via DEAE-52 and Sephacryl S-400 purification. Their molecular weight and polysaccharide content of these compounds were not obviously different, whereas the Se content of Se-GP11, Se-GP22 and Se-GP33 was 9.41, 6.59 and 16.25 times that of GP11, GP22 and GP33, respectively. The antioxidant activity of Se-GP for the DPPH, ABTS and hydroxyl radicals was higher than that of GP and was highest for the hydroxyl radical.

Development and growth of fruit bodies and crops of the button mushroom, Agaricus bisporus

We studied the appearance of fruit body primordia, the growth of individual fruit bodies and the development of the consecutive flushes of the crop. Relative growth, measured as cap expansion, was not constant. It started extremely rapidly, and slowed down to an exponential rate with diameter doubling of 1.7 d until fruit bodies showed maturation by veil breaking. Initially many outgrowing primordia were arrested, indicating nutritional competition. After reaching 10 mm diameter, no growth arrest occurred; all growing individuals, whether relatively large or small, showed an exponential increase of both cap diameter and biomass, until veil breaking. Biomass doubled in 0.8 d. Exponential growth indicates the absence of competition. Apparently there exist differential nutritional requirements for early growth and for later, continuing growth. Flushing was studied applying different picking sizes. An ordinary flushing pattern occurred at an immature picking size of 8 mm diameter (picking mushrooms once a day with a diameter above 8 mm). The smallest picking size yielded the highest number of mushrooms picked, confirming the competition and arrested growth of outgrowing primordia: competition seems less if outgrowing primordia are removed early. The flush duration (i.e. between the first and last picking moments) was not affected by picking size. At small picking size, the subsequent flushes were not fully separated in time but overlapped. Within 2 d after picking the first individuals of the first flush, primordia for the second flush started outgrowth. Our work supports the view that the acquisition of nutrients by the mycelium is demand rather than supply driven. For formation and early outgrowth of primordia, indications were found for an alternation of local and global control, at least in the casing layer. All these data combined, we postulate that flushing is the consequence of the depletion of some unknown specific nutrition required by outgrowing primordia.

신품종 큰느타리버섯 '곤지8호' 육성 및 특성

큰느타리버섯의 품종다양화와 국내 육성품종의 보급확대를 위해 2012년도에 육성한 신품종 "곤지 8호"의 특성을 조사한 결과, 균사생장적온은 <TEX>$23{\sim}26^{\circ}C$</TEX>, 버섯발생 및 생육적온은 <TEX>$15{\pm}1^{\circ}C$</TEX>였으며, 재배일수는 49 일로 대조품종보다 1일 짧았다. 병당 자실체 발생 개체수는 15.4개로 대조품종 보다 4.7개 많았고, 대 길이 120.3 mm로 대조품종보다 길었다. 자실체 물리성은 씹음성, 깨짐성, 경도 모두 대조품종보다 높았고, 특히 경도는 대조품종 대비 약 2배 높았다. 병당 수량은 132.5 g(900 cc/<TEX>$65{\Phi}$</TEX>), 170.8 g(1100cc/<TEX>$65{\Phi}$</TEX>)로 대조품종과 대등하였다. A new variety of Pleurotus eryngii which is named 'Gonji No. 8' was bred by mating monokaryotic strain isolated from E085D2 and a monokaryotic strain 'aerini No.3' obtained from the Mushroom Research Institute, Gyeonggi-Do A.R.E.S. The characteristics of the new variety 'Gonji No.8' is as follows. The optimum temperature for mycelium growth was from <TEX>$23^{\circ}C$</TEX> to <TEX>$26^{\circ}C$</TEX> on potato dextrose agar (PDA) medium. For the primodia formation and the growth of fruit bodies, the optimum temperature was from <TEX>$14^{\circ}C$</TEX> to <TEX>$16^{\circ}C$</TEX>. The period of spawn running was around 30 days at <TEX>$22^{\circ}C$</TEX> and the days taken after the removal of the spawn layer to initiate primodia was seven days. The hardness value of fruit body was <TEX>$8,432{\pm}2,193$</TEX> <TEX>$g/cm^2$</TEX>, which was two times more than that of 'Keunneutari No.2'. The yield of 'Gonji No.8' was about 133 g per bottle(900cc) and it was same as 'Keunneutari No.2'.

Purification of a lectin from fruit bodies of Lactarius pergamenus (Fr.) Fr. and studies of its properties

A lectin was purified from fruit bodies of the milk mushroom Lactarius pergamenus (Fr.) Fr. by a combination of ethanol precipitation, affinity chromatography on copolymer of polyvinyl alcohol and human blood B-group-specific substance, and ion-exchange chromatography on DEAE-Toyopearl. The lectin yield was 3 mg/kg of fresh mushrooms. Considerable loss of primary activity was observed during its purification, which, presumably, could be explained by disintegration of the lectin molecule, which consisted of six subunits, first to two molecules of three subunits, and then to individual subunits. There was a reverse tendency to aggregation during concentration of lectin solutions. Similar processes can take place in nature because of considerable individual variations of the lectin activity during growth of mushroom fruit bodies. The lectin weakly interacts with DGalNAc, while DGalβ1-3DGalNAc and DGalβ1-3DGlcNAc are the most probable candidates for ligands, with which the L. pergamenus lectin interacts at disaccharides level. The purified lectin may find application in histochemical research.

Effects of light and heavy metals on Cordyceps militaris fruit body growth in rice grain-based cultivation

The objective of this study was to examine the light and heavy metals on the fruit body growth of Cordyceps militaris in the rice-based cultivation. Since heavy metals are commonly detected in the paddy field, we investigated the effect of lead, cadmium and mercury on the rice grain-based cultivation of C. militaris. Cordycepin and cordycepic acid were determined by HPLC method. The result showed that the best fruit body growth and bioactive complements was obtained in rice I under 12 h light/dark cycle conditions. The effects of heavy metals (Pb, Hg, and Cd) to the fruit body were remarkable-the inhibition carried a dose-dependent behavior.

Search for new naturally occurring strains of Pleurotus to improve yields. Pleurotus albidus as a novel proposed species for mushroom production

Background The species of genus Pleurotus are worldwide cultivated. Aims To evaluate growth, yield production and morphological variations of fruiting bodies obtained from the cultivation of fourteen naturally occurring Pleurotus strains isolated from Argentina. Methods The strains growth was tested at different temperatures on Nobles’ medium. Substrates assayed were: supplemented Salix sawdust, supplemented and non supplemented wheat straw. The species studied were Pleurotus albidus, Pleurotus cystidiosus, Pleurotus djamor, Pleurotus ostreatus and Pleurotus pulmonarius. Results The maximum rate growth was reached by strains of P. pulmonarius, P. albidus, and P. ostreatus. No relationship was found when optimal mycelium growth, incubation time and yields were compared. The highest yield was obtained with P. albidus on wheat straw (biological efficiency 171.3%) which overcame in 82% the yield obtained for the commercial strain in the same substrate. When morphological variations were analyzed for each species, significant differences were found among strains. It was also possible to find a naturally occurring strain of P. ostreatus with better biological efficiency than the commercial strain assayed. Conclusions We propose the study of naturally occurring strains as a useful practice to improve yields of species of Pleurotus. Due to the high biological efficiency obtained we propose P. albidus as a new species for commercial production.

느타리버섯 병재배의 톱밥 대체 배지 재료 선발

In this study, we attempted to find substitute materials, swelling rice hull, cocopeat, corncob and coconut sawdust, for sawdust in bottle cultivation of Pleurotus ostreatus. Chemical characters of mixture substrates with four substitute materials for pine sawdust were not different significantly. By comparison in mycelial growth and yield of fruitbody, mixture substrate of cocopeat were showed the same level in P. ostreatus. Therefore, it is suggested that cocopeat was substituted for sawdust for cultivation of P. ostreatus.

Distribution of RNA, Nuclease and Phosphatase in Shii-take and These Changes during the Growth of Fruit Body

Distribution of RNA, Nuclease and Phosphatase in Shii-take and These Changes during the Growth of Fruit Body

RECOVERY OF MORE THAN 10 YEARS-DRYING Monascus CULTURES AND ITS PURIFICATION METHODS FROM FUNGAL AND BACTERIAL CONTAMINATION

This study was carried out to understand the recovery capability of more than 10 years- drying Monascus cultures. A new simple purification technique from fungal contamination using ethanol-soaking treatment was also reported as a part of this study. The result showed that all drying cultures were recovered well and retained their characters such as good growth, pigmen­tation and production of fruit bodies (ascomata), sexual spores (ascospores) and asexual spores. Several cultures showed its good growth in 20% ethanol medium. This study also reported suc­cessful purification of cultures from fungal contamination using ethanol-soaking treatment. This self-drying method, therefore, could be suggested as a good long-term preservation method for Monascus cultures. Moreover, purification method from fungal contamination soaked in ethanol 70% or 95% was successfully effective.

Argininosuccinate synthetase and argininosuccinate lyase: two ornithine cycle enzymes from Agaricus bisporus

Accumulation of high quantities of urea in fruiting bodies is a known feature of larger basidiomycetes. Argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL) are two ornithine cycle enzymes catalysing the last two steps in the arginine biosynthetic pathway. Arginine is the main precursor for urea formation. In this work the nucleotide sequences of the genes and corresponding cDNAs encoding argininosuccinate synthetase ( ass) and argininosuccinate lyase ( asl) from Agaricus bisporus were determined. Eight and six introns were present in the ass and asl gene, respectively. The location of four introns in the asl gene were conserved among vertebrate asl genes. Deduced amino acid sequences, representing the first homobasidiomycete ASS and ASL protein sequences, were analysed and compared with their counterparts in other organisms. The ass ORF encoded for a protein of 425 amino acids with a calculated molecular mass of 47 266 Da. An alignment with ASS proteins from other organisms revealed high similarity with fungal and mammalian ASS proteins, 61–63 % and 51–55 % identity, respectively. The asl open reading frame (ORF) encoded a protein of 464 amino acids with an calculated mass of 52 337 Da and similar to ASS shared the highest similarity with fungal ASL proteins, 59–60 % identity. Northern analyses of ass and asl during fruiting body formation and post-harvest development revealed that expression was significantly up-regulated from developmental stage 3 on for all the tissues studied. The expression reached a maximum at the later stages of fruiting body growth, stages 6 and 7. Both ass and asl genes were up-regulated within 3 h after harvest showing that the induction mechanism is very sensitive to the harvest event and emphasizes the importance of the arginine biosynthetic pathway/ornithine cycle in post-harvest physiology.

NaCl의 농도가 느타리버섯 자실체 발생 및 수량에 미치는 영향

This studies investigated the effect of concentrations of sodium chloride (NaCl) on occurrence and growth of fruitbody in oyster mushrooms, Pleurotus spp. Our experiments divided into two parts. When the water contents in substrate were added with sodium chloride solution in cotton waste box cultivation as a first experiment, the growth of mushroom was damaged as the concentration was increased, even though there was a little difference according to the strains. The yield in 1.0% NaCl solution was decreased to 72% compared to non-treated plot while that in 3.0% solution was only 2% of the non-treated plot. Morphological characteristics of mushrooms cultivated in substrate with the different concentration of the solution showed different results. For example, the size and thickness of pilei were not influenced by NaCl concentration, but the length of stipes and individual weight were much influenced. In plastic box cultivation filled with cotton waste, watering treatment with the different concentrations of sodium chloride solution, the second experiment, did not show any difference according to the concentration until 1.0% solution but there was a little difference according to the strains. The productivity of fruitbody started to decrease at 2.0% of the solution and the yield and quality of mushroom in 3.0% solution treatment were generally low. After the second flush, days for mushroom sprouting were generally prolonged in proportion to the solution concentration. Taken altogether, the second experiment did not show a clear effect as the case of the first experiment.

Fungal relationships and structural identity of their ectomycorrhizae

Aproximately 5,000–6,000 fungal species form ectomyorrhizae (ECM), the symbiotic organs with roots of predominantly trees. The contributing fungi are not evenly distributed over the system of fungi. Within Basidiomycota exclusively Hymenomycetes and within Ascomycota exclusively Ascomycetes contribute to the symbiosis. Hymenomycetes play a big part, Ascomycetes a minor role; Zygomycetes only form exceptionally ECM. Responsible for ascomycetous ECM are mostly Pezizales with their hypogeous derivatives, whereas Boletales, Gomphales, Thelephorales, Amanitaceae, Cantharellaceae, Cortinariaceae, Russulaceae, and Tricholomataceae are the most important ectomycorrhizal relationships within Hymenomycetes. ECM, as transmitting organs between soil and roots, are transporting carbohydrates for growth of mycelium and fruitbodies from roots and have to satisfy the tree’s demand for water and nutrients. The latter task particularly influences the structure of ECM as nutrients are patchily distributed in the soil and saprotrophic as well as ectomycorrhizal fungi can act as strong competitors for nutrients. In focusing these requirements, ECM developed variously structured hyphal sheaths around the roots, the so-called mantles, and differently organized mycelium that emanates from the mantle, the so-called extramatrical mycelium. The mantles can be plectenchymatous consisting of loosely woven, differently arranged hyphae or they are densely packed, forming a pseudoparenchyma similar to the epidermis of leaves. The extramatrical mycelium grows either as simple scattered hyphae from the mantle into the soil or it can be united to undifferentiated rhizomorphs with a small reach or to highly organized root-like organs with vessel-like hyphae for efficient water and nutrient transport from distances of decimeters. Cystidia, sterile and variously shaped hyphal ends, possibly appropriate for preventing animal attack, in addition, can cover mantles and rhizomorphs. Although only a limited number of species could be considered, some general conclusions are possible.

느타리버섯 자실체의 생육 및 미세구조에 미치는 온도의 영향

To elucidate the effect of temperature on the fruit body growth and structure of pleurotus ostreatus cultivar Chunchu No.2, microstructures were observed with scanning- and transmission electron microscope. Pileocystidia were well developed on the surface of pileus in the fruit body cultivated at . As the increasing temperature for fruit body development, thickness of pileus, thickness of stipes and length of stipes shown thin, thick and long, respectively. Color of pileus was also changes to whitish grown under high temperature. Physical structure shown as hardness and gumminess of stipes grown at high temperature, fruit body were soften than that of low temperature. Microstructures of fruit body grown at high temperature shown fast-discharge of basidiospore and sytoms aging. vacuolation in the cell observed at mycelium grown under high temperature. Optimum temperature for vegetative growth of fruit bodies were , and shown regular arrangement of mycelium on the surface of stipes.

Elevation of intracellular cAMP levels by dominant active heterotrimeric G protein alpha subunits ScGP-A and ScGP-C in homobasidiomycete, Schizophyllum commune.

In many fungi, the heterotrimeric G protein alpha subunits, and/or small G protein (RAS) control intracellular cAMP levels. But it is not clear which types of G proteins modulate cAMP levels in homobasidiomycete (mushrooms). To explain the mechanism, we expressed dominant active RAS (a homolog of S. cerevisiae RAS1) in homobasidiomycete Schizophyllum commune and compared the cAMP levels in the transformed clones with those of clones expressing dominant active heterotrimeric G protein alpha subunits ScGP-A, B, and C. The results demonstrated that the dominant active ScGP-A and C elevated the intracellular cAMP levels. In contrast, the dominant active S. commune RAS gene did not affect the cAMP levels, even though colony growth and formation of fruiting bodies were apparently repressed. These data suggest that the heterotrimeric G protein alpha subunits are involved in the mechanism of cAMP regulation, and that RAS modulates another signal-transduction pathway regulating cell growth and differentiation.